In an image forming apparatus represented by a laser printer or a copying machine, a process cartridge which is attachable to and detachable from a main body of the image forming apparatus (hereinafter, referred to as an “apparatus main body”) is provided.
The process cartridge is a member which forms content to be expressed, such as letters or figures and transfers the content to a recording medium, such as a paper sheet. Here, in the process cartridge, a photoreceptor drum in which the content to be transferred is formed, is included, and various means for forming the content to be transferred by acting on the photoreceptor drum are also disposed. Examples thereof include means for performing developing, charging, and cleaning.
In regard to the process cartridge, the same process cartridge is attached to and detached from the apparatus main body in maintenance, or a new process cartridge for replacement is mounted on the apparatus main body after an old process cartridge is disengaged from the apparatus main body. The attachment and detachment of the process cartridge are performed by users of the image forming apparatus manually, and thus, it is desirable that the attachment and detachment can be easily performed as much as possible.
Meanwhile, it is necessary that the photoreceptor drum included in the process cartridge rotates around an axis during the operation thereof. Therefore, a driving shaft of an apparatus main body is engaged with the photoreceptor drum directly or via another member at least during the operation, and the photoreceptor drum is configured to receive a rotating force from the driving shaft and rotate. Therefore, in order to attach and detach the process cartridge to and from the apparatus main body, it is necessary to release (disengage) the engagement between the driving shaft of the apparatus main body and the photoreceptor drum, and to mount the process cartridge again for every attachment and detachment.
Here, if it is possible to attach and detach the photoreceptor drum by moving the photoreceptor drum (process cartridge) in an axial direction of the driving shaft of the apparatus main body, a structure for the above-described attachment and detachment is relatively simple. However, from the viewpoint of reducing the size of the image forming apparatus and ensuring space for the attachment and detachment of the process cartridge, it is preferable that the process cartridge is disengaged from the apparatus main body by pulling out the process cartridge in a direction different from the axial direction of the driving shaft, and that the process cartridge is mounted on the apparatus main body by pushing the process cartridge in this direction.
In PTL 1, a technique in which a driving force can be transmitted to a photoreceptor drum from an apparatus main body side when a cover of the apparatus main body is closed, and movement of separating a rotating body is performed such that the driving force is not transmitted to the photoreceptor drum when the cover is open, is disclosed. Accordingly, it is possible to attach and detach a process cartridge to and from the apparatus main body in the direction different from the axial direction of the driving shaft.
In PTL 2, a technique in which a gear is provided in a photoreceptor drum, and the photoreceptor drum rotates with the gear meshing with a gear driven by the apparatus main body, is disclosed.
In addition, in PTL 3, an invention in which a driving shaft of an apparatus main body and a photoreceptor drum are engaged with each other via a rotating force transmission component having a trunnion structure and attached to the photoreceptor drum, and the photoreceptor drum rotates, is disclosed. Since the angle of the rotating force transmission component with respect to an axis of the photoreceptor drum can be changed by using the trunnion structure, the engagement and disengagement between the driving shaft of the apparatus main body and the photoreceptor drum are easily performed.
In PTL 4, a coupling which has a hook-like part engaged with a driving shaft, swings around two axes orthogonal to an axis of the driving shaft, and can move in an axial direction of the driving shaft, is disclosed. PTL 4 discloses that the engagement and disengagement between the driving shaft of the apparatus main body and the photoreceptor drum becomes easy due to this structure.
In NPL 1, a technology in which a bearing member engaged with a driving shaft is provided to be movable in an axial direction by using an elastic member, such as a spring, is disclosed. Accordingly, when attaching and detaching the bearing member and the driving shaft to and from each other, the bearing member moves and retreats in the axial direction while being biased by the elastic member so that the attachment and detachment are smoothly performed.